The present invention relates generally to actuation levers and more particularly to an actuation lever having a knob fixedly secured thereto.
Actuation levers that include a lever and a knob secured thereto are well known in the art. Many manufactures and/or purchasers of actuation levers typically require the knob installation force, i.e. the force required to seat a knob onto a lever, be small enough to manually install a knob without the aid of a force multiplier tool, such as a press. Similarly, the knob removal force, i.e. the force required to remove a knob from a lever, is typically required to be large enough to prevent inadvertent removal of the knob during use.
One means of securing a knob to a lever comprises the use of an adhesive to chemically bond a knob to a mating lever. The pre-cured properties of an adhesive permit a knob to be installed onto a lever with minimum force. Moreover, the retaining force of a cured adhesive readily satisfies typical minimum removal force requirements. However, application of an adhesive can be costly, given the recurring costs of the adhesive, disposable dispensing equipment, and labor. Further, the adhesive application process is vulnerable to errors, i.e. the adhesive dispenser or assembly operator may dispense too much, not enough, or no adhesive at all.
Another means of securing a knob to a lever comprises the use of a mechanical interference fit between the knob and lever. In this design, one end of a lever is typically slightly larger in geometry than a knob cavity into which the lever is inserted, thereby creating frictional interference between the two mating parts. While the use of an interference fit to secure a knob to a lever overcomes the shortcomings of using an adhesive, it does not readily satisfy specified installation and removal force requirements simultaneously. In other words, a significant interference between a lever and a knob required to satisfy a specified minimum removal force typically causes the installation force to exceed a specified maximum value. An excessively high installation force can damage the lever-actuated device, the knob being installed, or may require a force multiplier tool to install the knob.
Another means of securing a knob to a lever comprises the use of a metal retaining clip or spring designed to serve as a mechanical attachment between a knob and lever. While a spring or clip overcomes the shortcomings of an adhesive or an interference fit, it requires additional labor to assemble and adds material cost to the final product.
The present invention provides an improved actuation lever incorporating a cost-effective means of attaching a knob to a mating lever while simultaneously providing robust knob retention characteristics and an installation force low enough to manually install a knob without the aid of a force multiplier tool. In a preferred embodiment, the actuation lever comprises a lever having a first end configured to engage and support a knob, a second end configured for connection to a lever-actuated device, and a longitudinal axis. The knob includes at least one pocket having at least one inner peripheral surface. The first end of the lever includes a resiliently deflectable retaining member having a resilient tine. As the knob is inserted onto the first end of the lever, the tine deflects inwardly towards the longitudinal axis. The spring force generated by the deflected tine causes the retaining member to exert oppositely directed forces against the inner peripheral surface of the pocket. A sharply pointed tip on the end of the tine imbeds into the inner peripheral surface of the pocket to retain the knob on the first end of the lever.
Various additional aspects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description:
FIG. 1 is a perspective view of an actuation lever according to a preferred embodiment of the present invention showing a knob and a lever.
FIG. 2 is a perspective view showing a cross-section of the knob according to the preferred embodiment.
FIG. 3A is an elevation view of a lever according to the preferred embodiment prior to installation of the knob.
FIG. 3B is a cross-sectional view of a knob installed on a lever according to the preferred embodiment.
FIG. 4 is a top view of a lever secured to a device prior to installation of a knob.
FIG. 5 is a perspective view of a lever secured to a lever-actuated device prior to installation of a knob.